Manufacture of rifled tubes



Jan.4,f193s. Mmc@ v 2,104,3191v MANUFACTURE OF RIlF-LED TUBES f Filed Feb. 1o, 1934 l, mu

8 l l si 9 l it-N JNVE T" ALLEN A. CKE

Patented Jan'. 4, 1938 UNITED STATES 2,104,319 MANUFACTUBE F RIFLED TUBES Allen A. Dicke, Montclair, N. J., Company, Inc.,

ingtonArml Delaware assigner to Bema corporation of Appumiwrebmrr- 1o, me smsafilia. 710,003

' s claims. (ci. zii-1.1)

This invention relates to manufacture of riiled tubes. The invention is of special application to the manufacture of rifle barrels. Rifle barrels, as usually constructed, are made by iirst drilling 6 a hole through a steel rod and enlarging the hole to the correct size as by reaming. lThereafter riiling grooves are formed by means of a cutting tool which is drawn longitudinally through the barrel while the tool, or the barrel, is rotated,

with the result that a helical groove is formed. These toolaare necessarilydelicate, and for this reason it is necessary to take a very small cut whichv necessitates passing the rifiing tool back and forth through the barrel a large number of times. .This operation must be repeated for each groove or at least for each pair of grooves.

More recentlyit has been suggested that'stainless steel be used as rifle barrel material to resist `the corrosive actionof certain residues left in ,20 the barrel from the combustion of the powder or the priming composition. Asis well known, stainless steels are comparatively diilicult to machine, particularlythose stainless steels which have the necessary hardness to resist the erosion and wearv to which rie barrels are subjected.

Another disadvantage in the use oi stainless steel as rie barrel material is its comparatively high cost.

It is an object of the present invention to avoid the expense and diiilculty of machining rifle grooves in rifle barrels particularly such barrels when made of stainless-steel.

Another object is to produce by swaging, or other means, an internally grooved tube of relatively thin material, the external surface of which is smooth so that said tube may be inserted in a tube of heavierfand preferably lessI expensive, material for the purpose of forming a riile barrel.

It is a further object to produce this result' by placing' a tube of suitable material over a mandrel formed with projections, such as ribs. of a size, shape and location corresponding to the 'conguration desired on the inside of the tube and thereupon swaging or otherwise contracting the tube upon the mandrel in such a way that the internal surface thereof lies closely adiacent andf'corres 5o sponds with the external surface of the mandrel. /l

A further object is to utilize said process and apparatus for producing not only the riiling grooves, but if desired, also the correct shape and dimensions ofthe 'chamber and throat oi the 55 barrel. i' t Aof Fig, 1, looking in 'and The invention will be understood from the attached drawing wherein:

Fig. 1 illustrates, partly in section, an apparatus 'capable of carrying out the process;

Fig. 2 is a cross-sectional view on the line 2--2 5 the direction of the arrows;

Fig. 3 is a cross-sectional view on the line 3`3 of Fig. 1,1ookingin the direction of the arrows;

Fig. 4 is a cross-sectional view showing the chamber and throat portion of the tube and a 10 portion of the mandrel utilized for that purpose:

Fig. 5 illustrates a modification oi the process and apparatus.

In said drawing, the numeral I0 designates gen- 15 erally a mandrel of relatively hard material provided, in the form shown, with raised helically disposed ribs II of any suitable form, construction and dimensions which may be required for the production of the grooves or other coniigura- 20 tion desired within the tube to be made. The numeral I2 designates generally a tube partly compressed upon the mandrel. As will be noted in Fig. 2, the tube l2 is originally of such an internal diameter as to just receive the mandrel Ill 25 and ribs Ii. The tube is now compressed upon the mandrel by any suitable means such as swaging or by pushing or drawing the mandrel and tube one or more times through a compressing die. If a. swaging machine is used the mandrel 30 with the tube thereon is simply passed through the swaging machine which delivers a very vlarge number of blows or squeezes upon the tube to cause it to be' contracted and to liein close proximity to the mandrel at all points so that it '3"' assumes an internal coniiguration the reverse of the mandrel. The result ofssuch a compressing operation is indicated in Fig. 3. It will b e noted thatthe external diameter of the tube has been slightly reduced tc supply the material which has 40l been caused to flow between the ribs i I. One apparatus for producing this eect is shown, more or less schematically, in Fig. 1, wherein the member i3 may be understood to be the tool chuck of an ordinary broaching machine to which the '45 mandrel I0 may be attached by any suitable means as by the key i4. l5 represents a compressing die which may be formed of one or more working surfaces. In the form shown the section l5.. is more or less chamfered to facilitate the ent v of the uncontracted tube into the die. Section i6 indicates the approximately conical compressing section "wherein the tube is contraeted from its original external diameter to its -ber guns the mandrel may be-o'f nal external diameter. Section I5 is preferably cylindrical and serves as ,a burnishing die. 'Ihe die I5 may be held in any usual die holder as used `in breaching machines for internal broac'hing,

and if desired, may be provided with an anti-friction thrust bearing, as bearing balls I6, located in grooves in the die I5 and the annular member I1, which may be formed with a cylindrical extension I8 and locking ring I9 to keep the parts in assembled relationship. If desired, positive gearing or other connecting means maybe provided to rotate the die in accordance with the lead of the riiiing, or in such direction and at such speed as may be desirable to secure the best results under any particular circumstances. In the form of apparatus shown, it is desirable to' have a collar or bushing diameter at least as small as-the ilnished diameter of the tube so that the entire tube can be drawn through the die. Furthermore, an abutment, such as the collar 2i, should be provided which may be attached to the mandrel by any suitable attaching means such as the key 22.

In carrying outv the process, the mandrel would preferably be removed from the clutch I3 ofthe drawing head, the collars 20 and 2| put in place and thereupon the tube slipped over the mandrel. Thereafter the forward end of the mandrel would be passed through the die and inserted into clutch I3 and clutched in place, it being understood that at this time the clutch I3 is in its extreme left position and quite close .to the die. At this time the forward end of the tube is ready to enter the die. The machine is now started and the mandrel with tube thereon is slowly drawn through the die until the entire length of the tube has passed through the die. Thereupon the collar 2| may be removed and the die removed from its holder. If it is desired to use the same machine to withdraw the mandrel from the tube the machine is reversed and the chuck I3 returned to its original removed from the chuck and a plain cylindrical stripping die substituted for the die shown. This collar will have an internal diameter just large enough to clear the ribs il; Thereupon the machine is started and the mandrel Awithdrawn from the tube. If a split stripping die is'used it will not be necessary to remove the mandrel from the chuck. As the mandrel is withdrawn the tube and mandrel must be rotated relative to each other. This may be provided for by an anti-friction thrust bearing or by positive gearing or other means for rotating the die relative to the mandrel.

Ii' the cartridge body is not much larger thanv the diameter of the bore. as is the case, for example, in .22 caliber ammunition, it is possible to use this process for forming not only' the barrel proper, but also the chamber and throat. In this case, the rear portion of the mandrel is made; as shown in Fig. 4, with an enlargedI section I0. for producing the chamber and also with ar conical section IU for forming the throat.

In. the drawing the dimensions of the height of ribs II have been somewhat exaggerated in order to maket le`.drawing more clearly understood. In practice the .depth of grooves is usually proportionately less than shown.

In the form shown in Fig. 1, the force required to pass the tube I2 through the die is transmitted through the mandrel Il; As in small calismall diameter: itwis sometimes desirable to avoid this. Furthermore, in the form of Pig. I, the tube'is in corn- 20 located upon the mandrel of av position, the mandrel pression which is notusually desirable. These objections are overcome in the 'form of apparatus shown in Fig. 5 wherein the mandrel is not subjected to either tension or longitudinal compression. With the use of this form of apparatus the tube is preferably first slightly reduced at its forward end, as shown at IZB, by any usual method and apparatus, such as an ordinary swaging machine. 'I'he forward portion I 2B of the reduced :section is attached to the drawing head of the machine by any suitable means such as by being clamped into the clamping .jaw clutch I3B carried by the drawinghead of the machine. 'Ihe section IZB" of th reduced section is oi sumcient length to permi the passing of the tube through the die and into the clamping clutch when the clutch is returned to a position adjacent the die. ,The mandrel I 0B is merely laid more or less loosely within the tube. With this apparatus the tube is under considerable tension which improves the reducing operation. In this case an abutment such as the collars 20 and 2| of Fig. 1 is not necessary. After the vtube has passed through the die the mandrel will be withdrawn preferably by applying tension to the end thereof. .The forward end of the tube I2B is, of course, unusable and will be cut 'oil'.

The resulting rifled tube is of rather small wall thickness and can, therefore. not always be used ais the barrel of a firearm. In such cases. the tube, made as described above, may be inserted into a larger tube of apprbpriate wall thickness so that the two tubes comprise the barrel proper.

.Barrels for certain uses, particularly for machine guns wear out rather rapidly and as a result must be thrown away and new barrels substituted. -By using tubes made according lto the present invention, it is merely necessary to withdraw the ried tube and insert a newv one in its place.

However, it is not always essential that such riiled tube be inserted into another tube. as these relatively thin walled tubes may, in some cases, be used without a surrounding and coniining tube, as for example, as barrels of air guns or in many connections where an internally riiled or otherwise grooved tube of relatively. small wall thickness is required. Among other uses of the invention are the production of bear-ing bushings with o'il grooves. While in the form illustrated the interna-l configuration of the tube produced comprises helical grooves formed by the helical ribs II, it is to be understood that any other configuration may be produced which is of such a nature that the mandrel may be withdrawn from the tube. Y J

While preferred forms of e invention have been illustrated and describetd? above, it.will be apparent that changes and modifications may be made in the form of apparatus and in the steps of the process without departing from the spirit Aand scope ,of .the invention.

,grooves and thereupon removing the mandrel from the tube.

2. The process of making a rifle barrel formed together will with internal helical grooves and an enlarged-7l the diameter of said tube at one end, placing said reducedend into the chuck of a, drawing ma4v chine, placing within said tube a. mandrel formed with a reversed riing, and thereupon pulling said tube and mandrel together through a. reducing die, whereby the tube is compressed upon the mandrel and its interior surface formed with the desired rifiing, removing the mandrel from the tube and cutting off the reduced end portion.

ALLEN A. DICKE. 

